10823 update slack installation doc

[sanchariGr]

Proposed changes:

• As a fix for this Issue, there is a small update that was needed to the docs.

Status (please check what you already did):

• added some tests for the functionality
• updated the documentation
• updated the changelog (please check changelog for instructions)
• reformat files using black (please check Readme for instructions)

[CLAassistant]

All committers have signed the CLA.

[ancalita]

Looks great 🙌🏼 Could you also add a doc changelog entry, guidelines are here: https://github.com/RasaHQ/rasa/blob/main/changelog/README.md

[sanchariGr]

Looks great 🙌🏼 Could you also add a doc changelog entry, guidelines are here: https://github.com/RasaHQ/rasa/blob/main/changelog/README.md

sorry missed that, on it 👍

[indam23]

From the issue, do we need to add more permissions to the end of the section too?

[sanchariGr]

From the issue, do we need to add more permissions to the end of the section too?

@melindaloubser1 I tried both with and without the added permissions mentioned in the issue and it worked both times so i believe whatever was causing this was fixed by slack themselves, and so we dont need to add any other permissions.

[m-vdb]

woot woot first PR on Open Source @sanchariGr 🎉